Two-mode squeezing and SU(1,1) interferometry with trapped ions
Jeremy Metzner, A. Quinn, S. Brudney, I. D. Moore, S. C. Burd, D. J. Wineland, D. T. C. Allcock
Abstract
We experimentally implement circuits of one- and two-mode operations on two motional modes of a single trapped ion. This is achieved by implementing the required displacement, squeezing, two-mode squeezing, and beam-splitter operations using oscillating electric potentials applied to the trap electrodes. The resulting electric fields drive the modes resonantly or parametrically without the need for optical forces. As a demonstration, we implement SU(2) and SU(1,1) interferometers with phase sensitivities near the Cram\'er-Rao bound. We report a maximum sensitivity of a SU(2) interferometer within 0.67(5) dB of the standard quantum limit (SQL) as well as a single- and two-mode SU(1,1) sensitivity of 5.9(2) dB and 4.5(2) dB below the SQL, respectively.